Total Artificial Heart (TAH) and related devices (e.g., ventricular assist device) are emerging that provide the potential for almost unlimited patient mobility and near-normal lifestyle for the patient. The new devices being developed are totally implantable, self-contained (battery is external), electrically driven systems. However, the power and energy density requirements of the new devices are high and in many cases exceed the best battery technology available today. The proposed research in this program seeks to develop novel primary batteries with three times the energy density of existing primary batteries. In Phase I we will demonstrate feasibility of enhanced battery components and obtain participation of major battery manufacturer. In Phase II we will integrate enhanced battery components into prototype battery and demonstrate improved performance compared to conventional batteries. In Phase I we will demonstrate feasibility of enhanced battery components as well as enhanced performance of laboratory batteries. In Phase II we will integrate enhanced battery components into prototype batteries and in field tests demonstrate improved performance compared to controls. Both phase I and Phase II programs will be enhanced by our recent addition of both commercial battery partner and commercial blood pump expert.